Insert portage structure category & package directories. For example i want to fix apparmor to include the very latest source, you would mkdir -p /var/overlay/local/sys-apps/apparmor then copy the old ebuild you found online (or on your computer) to the directory. /var/overlay/local/sys-apps/apparmor/apparmor-2.8.4.ebuild is where the old ebuild would sit. Copy it to the latest upstream version number. cp apparmor-2.8.4.ebuild apparmor-2.9.2.ebuild then run the ebuild manifest file.